The raspiness on my car has gone out of control. You guys can see all the performance I have on my Z at my signature. I don't know if something is going wrong with my exhaust set-up, but I need you guys inputs. Is anyone running a similar set-up on their Z's, what are your impressions?

 

i know i would be embarassed, if i was rasping

 

Test pipes

 

Is there anything I can do to my exhaust to reduce the raspiness. I was thinking like an H or X pipe welded into my true dual. What kind of performance I'm going to loose if I go this way.

 

You'll loose bottom end power. This is a good example which proves that true dual exhausts will develop raspiness just as non-true dual ones do. Godd luck.

 

Ever hear a modified M3? it sounds raspi as hell too.

 

Dont flame, but what is "raspy"

 

+1

 

Rasp is an ambiguous term used to describe the sound of an exhaust system.

 

The sound that you got is the sound that you got.

If you want to buy and swap components searching for a different sound, it gets expensive. Best wishes.

 

Part of the problem is you have a 2.5 Inch Res. Test Pipe, and a 2 inch exhaust system and your exhaust system is not going to flow well at all. I installed a set of our Res. Test Pipes on a car with your same cat back. We had same result you have. The customer loved it though. After looking at that cat back I scratched my head and asked myself how anyone could put that on their car. Please, don't take that the wrong way I just spend every day fabricating exhaust and when I see an opportunity to improve flow I utilize it and the Invidia 2000 is not a good flowing system. (Good craftsmanship though). The way I see it you have two choices, either pull our Res. Test Pipes off and put something more restrictive on, or step up to a true dual exhaust system, Ingen, H.K.S. High Power, our Intimidator, or even the Stillen. The bottom line is the combonation you have is not working for you...Tony

 

Get some high flow cats. You don't need test pipes without a forced induction setup, anyway.

 

dont need it, but its so much better price and performance wise.
Anyway, to minimize rasp, throw in a resonated X pipe and it'll become as quiet as it was prior to the TP and it'll be just as fast.

 

The problem is your catback or your test pipes depending how you wanted to look at it. The exhaust isn't controlling the exhaust note well enough to keep the rasp down. if you must keep the test pipes, put your complete stock catback on or get another catback that isnt' as raspy.

On the otherhand, if you put back in your stock cats, that would make up for the exhaust and would control the rasp.

IMHO, messing with n/a parts isn't even worth it. If I were you and wanted to run that exhaust, throw the stock cats back on and be done with it.

As was noted, an H-pipe would most likely help the situation.

 

^^+1 -

Good advice and your right on the mark there. The thing that causes rasp is when you change the pulse and flow and the system can't handle it. Balancing the system better can help, via an X-pipe, which is best for our cars. A resonated X is even better, and likely a best choice, that won't harm performance.

The issue again, will be pipe size - honestly, with headers and the rest of your mods - you have the wrong catback in place. You need one that will handle the flow - and that will be a 2 1/2" system, like Tony wrote earlier.

Rick

 

For the guys that test, design and build this stuff, is there a rule of thumb regarding the exhaust note or performance hat coincides with:
1) True Dual
2) Two into 1
3) Pipe diameter on @ of the above

Realizing there are so many factors involved, I thought you may have found some consistencies in your testing. i.e. small pipe = higher pitch or single 3" dia = hp gain in lower RPMs and same power up top vs. a 2 3/8 dia.....or?

I used to do 2 stroke exhaust testing on my flat tracker short track bike and found that we could predict results relatively well after testing different designs. Need high end hp do this, need torque, do that type of thing.

 

OK - several answers to possible questions you have here. the short answer is yes...but no as well.

1 - It flows better and will usually cover from about 250HP to upwards of 450-500HP - but dependant on pipe size, engine, and build and mods. Exhaust note here will depend on engine, build, mods and most importantly how the exhaust devices are built.

2 - Single exhaust - like our cars some with - good to a certain amount of HP, like #1 - also dependant on pipe size, etc. 3" single will perform very similarly to 2.5" dual - but with effective Xpipes, etc..the dual will do a better job of scavenging - and therefore, flow better.

I hope this starts or answers your question. There are lots of things to consider, to answer the question, and teh question was pretty general as well. I can give more - just let me know.

Also, check out this link:
http://www.nsxprime.com/FAQ/Miscella...austtheory.htm


Rick

 

While we're on the subject.. where can I find a good resonated X-pipe?

 

MagnaFlow makes them....call Tony at the shop and he can send one out to you if you want.

Rick

 

Sweet, are they resonated? I'm also thinking about doing weld-in hi high flow cats.